Enhanced multiframe alignment for tandem connection trials

Abstract

According to the invention a synchronous hierarchic network system and a method of transmitting data are disclosed using at least a path segment between a first network element and at least a second network element on which a tandem connection monitoring method is established for monitoring information over said path segment, and means for minimizing the signal interruption due to a loss of multiframe alignment subsequent to an interruption, distortion or switching operation of the signal transmission path.

What is claimed is:  
     
       1. A method of transmitting data in a synchronous hierarchic network system comprising at least a path segment between a first network element and at least a second network element, said method comprising: 
       establishing a tandem connection monitoring method for monitoring transmission of information over said path segment, and  
       detecting an aligned signal reception or an in multiframe signal transmission state subsequent to an interruption, distortion or switching of the signal transmission path on the basis of a first received frame alignment signal (FAS) value by  
       performing a frame alignment search independent of a presumed position of the frame alignment signal, wherein every detected frame alignment signal (FAS) is accepted as a valid frame alignment signal (FAS).  
     
     
       2. The method of transmitting data according to  claim 1  comprising, 
       generating of a further “In Multiframe  2  (IM 2 )” state signal to handle a switching situation in which a protection switch action happens at a moment when new and old frame alignment signals (FAS) overlap and the new frame alignment signal (FAS) is received later in time than the old frame so as to avoid that the state machine enters an out of multiframe (OOM) state.  
     
     
       3. The method of transmitting data according to one of  claim 2 , wherein the “In Multiframe  2  (IM 2 )” state is used to extend the detection period for the new frame alignment of the received signal subsequent to said alteration. 
     
     
       4. The method of transmitting data according to one of  claim 1 , wherein an out of multiframe (OOM) state is not entered for a certain time interval upon detection thereof. 
     
     
       5. The method of transmitting data according to one of  claim 4 , wherein no associated standardized subsequent actions are initiated upon initial detection of said OOM state. 
     
     
       6. The method of transmitting data according to one of  claim 5 , wherein said associated standardized subsequent actions include all-ones insertion. 
     
     
       7. A synchronous hierarchic network system especially adapted for to a data transmission comprising 
       at least a path segment between a first network element and at least a second network element on which a tandem connection monitoring method is established for monitoring information over said path segment, and  
       means for detecting, for reduction of signal interruption due to loss of multiframe alignment, an aligned signal reception or an in multiframe signal transmission state subsequent to an interruption, distortion or switching alteration of the signal transmission path on the basis of the detection of the first received frame alignment signal (FAS) value independent of a presumed position of the frame alignment signal, and  
       means for accepting every received frame alignment signal as a valid frame alignment signal.  
     
     
       8. The synchronous hierarchic network system according to  claim 7  comprising means for generating a further “In Multiframe  2  (IM 2 )” state signal and wherein during the further “In Multiframe  2  (IM 2 )” state or upon signalling of the further “In Multiframe  2  (IM 2 )” state signal the detection period for a anew received frame alignment signal (FAS) is extended. 
     
     
       9. A method of transmitting data in a synchronous hierarchic network system comprising at least a path segment between a first network element and at least a second network element, said method comprising: 
       establishing a tandem connection monitoring method for monitoring transmission of information over said path segment,  
       detecting an aligned signal reception or an in multiframe signal transmission state subsequent to an alteration of the signal transmission path on the basis of a first received frame alignment signal (FAS) value, and  
       generating of a further “In Multiframe  2  (IM 2 )” state signal to handle a switching situation in which a protection switch action happens at a moment when new and old frame alignment signals (FAS) overlap and the new frame alignment signal (FAS) is received later in time than the old frame so as to avoid that the state machine enters an out of multiframe (OOM) state.  
     
     
       10. The method of transmitting data according to  claim 9 , wherein the “In Multiframe  2  (IM 2 )” state is used to extend the detection new frame alignment of the received signal subsequent to said alteration.